docs: def get_kbs(custom_kbs_files=None, cache={}):  # noqa
      """Load kbs (with caching).
  
      This function stores the loaded kbs into the cache variable
      For the caching to work, it needs to receive an empty dictionary
      as "cache" paramater.
      """
  
      cache_key = make_cache_key(custom_kbs_files)
      if cache_key not in cache:
          # Build paths from defaults and specified ones
          kbs_files = CFG_REFEXTRACT_KBS.copy()
          if custom_kbs_files:
              for key, path in custom_kbs_files.items():
                  if path:
                      kbs_files[key] = path
          # Loads kbs from those paths
          cache[cache_key] = load_kbs(kbs_files)
      return cache[cache_key]